The long-term goal of this proposal is to reduce the risk for osteopenia and fracture in patients with juvenile rheumatoid arthritis (JRA). The first steps toward this goal are to characterize the natural history of bone disease in JRA and identify, those risk factors which predict reduced bone mass. Strategies for intervention in the prevention and treatment of osteopenia will be derived from the course of skeletal development obtained through sequential measurements of bone mineral density (BMD). The specific aims of this proposal are; (1) to determine whether patients with JRA have a decreased rate of skeletal growth and development by comparing rates of change in BMD to a control group of children; (2) to identify the factors that contribute to abnormalities in bone density and metabolism in the JRA patient population; (3) to characterize bone formation and resorption dynamics through sequential measurement of bone biochemical markers of osteoblastic and osteoclastic activities. The change in BMD in JRA patients versus controls will be compared by performance of analysis of covariance. The impact of putative risk factors on BMD will be evaluated by univariate analysis and by construction of a multivariable model. The primary sponsor for this proposal, Dr. Murray J. Favus, is an accomplished researcher in the field of bone metabolism and bone diseases. Dr. Favus will guide Dr. Rabinovich in the investigation of bone disorders and risk factors for osteoporosis in patients with JRA. Dr. Karrison, the secondary sponsor, is a biostatistician with extensive experience in clinical studies via his research and his work with the Institutional Review Board and the Clinical Research Center (CRC) at the University of Chicago. Dr. Karrison will guide Dr. Rabinovich as she extends her expertise in the field of data analysis. Under the tutelage of Drs. Favus and karrison, Dr. Rabinovich will strive to become a successful independent clinical investigator in the fields of pediatric rheumatology and bone disorders. Dr. Rabinovich has outlined a plan for formal didactic teaching including enrollment in a course sponsored by the CRC entitled "Essentials of Clinical Research", through participation in the Robert Woods Johnson Clinical Scholars Program and by enrollment in a biostatistics course taught by Dr. Karrison. This coursework will augment Dr. Rabinovich's knowledge in health services research, medical ethics, research design, biostatistics and outcome studies. In addition, Dr. Rabinovich will attend weekly interactive seminars at the U of C entitled "Seminars in Health Studies" and remain an active participant in a series of meetings with the Bone Working Group. Dr. Rabinovich's background and experience summarized in the biographical sketch support her participation in the Mentored Clinical Scientist Development program. Dr. Rabinovich has unique abilities, including formal training in epidemiology through the pursuit of a Master's in Public Health in epidemiology. She is board certified in a pediatric rheumatology, a well rounded clinician and teacher. She is developing expertise in the field of bone disorders. Her long term career plans are to pursue a career in academic medicine encompassing clinical research, teaching, and patient care. The Mentored Clinical Scientist Development Award will aid Dr. Rabinovich as she strives to develop into an independent investigator.